Carboxyhemoglobin caused by smoking nonnicotine cigarettes. Effects in angina pectoris.

SUMMARY The effects of increased carboxyhemoglobin levels caused by smoking nonnicotine cigarettes upon exercise-induced angina were investigated in 10 patients. The mean carboxyhemoglobin level after smoking eight nonnicotine cigarettes, one every 30 minutes, rose from 1.58 to 7.79%. Smoking significantly decreased the mean exercise time from the onset of exercise until the onset of angina from 109.8 to 83.5 seconds. There was significantly less of an increase in systolic blood pressure, heart rate, and product of systolic blood pressure times heart rate after exercise-induced angina after smoking compared to the nonsmoking state. Smoking nonnicotine cigarettes increased the carboxyhemoglobin level, decreasing the rate of oxygen deliverability to the myocardium, with angina developing sooner, following less cardiac work. Nicotine Coronary heart disease Exercise S MOKING one high-nicotine' or one low-nicotine2 cigarette caused patients with angina pectoris due to coronary heart disease to have a significant decrease in exercise performance before the onset of angina. Smoking one nonnicotine lettuce-leaf ciga-rette3 did not cause any significant change in exercise performance in these patients before the onset of angina. Smoking high-nicotine, low-nicotine, or non-nicotine lettuce-leaf cigarettes caused a significant similar increase in carboxyhemoglobin levels in normal subjects4 and in patients with angina pectoris due to coronary heart disease.5 The presence of increased carboxyhemoglobin probably reduces the amount of oxygen 782 deliverable to the myocardium. Therefore, this study was performed to determine whether patients with angina pectoris would have any significant difference in exercise performance after serial smoking of nonnicotine lettuce-leaf cigarettes, compared to the nonsmoking state. Materials and Methods Ten men, all of whom had smoked at least 20 cigarettes daily for at least 19 years, were subjects. Each subject had a classical history of exertional angina pectoris. Five patients had a previously documented transmural myocardial infarction, at least 2 years old. The other five subjects had coronary artery disease documented by previous coronary angiography, with 50% or greater narrowing of the lumen of at least one major vessel. The subjects were familiarized with the equipment and the procedure and had practiced exercising on the bicycle ergometer before the study was begun. The studies were performed on four consecutive mornings. Smoking was performed on two mornings. The order of the two smoking and the two nonsmoking mornings was randomized. Smoking was not permitted for at least 12 hours prior to the onset of the study each morning and was not permitted during the study